Preparation method and application of ionic metal organic framework material

Abstract

The invention discloses a preparation method of an ionic metal organic framework material, which comprises the following steps: mixing nitric acid metal salt, pyrazine carboxylic acid and 1, 4-diazabicyclo [2.2. 2] octane in a solvent, ultrasonically dissolving, transferring into a hydrothermal reaction kettle, heating and reacting at 120-150 DEG C, cooling to room temperature, carrying out solid-liquid separation, washing the solid with the solvent, and drying to obtain the ionic metal organic framework material. And mixing the dried product and a halogen derivative in acetonitrile, reacting in a nitrogen atmosphere at 60-80 DEG C, cooling to room temperature, collecting a solid product, washing, and drying in vacuum to obtain the ionic metal organic framework material. The ionic metal organic framework material not only can be used as a catalyst to catalyze the cycloaddition reaction of carbon dioxide and an epoxy compound to prepare cyclic carbonate, but also can catalyze the copolymerization of sulfur dioxide and epoxide to generate polysulfite; and in the catalytic reaction, the catalyst has the advantages of good catalytic activity, high selectivity, small dosage and wide substrate universality.

Description

Technical Field

[0001] The present invention relates to a preparation method of a multi-active center ionic metal organic framework material and its application in catalyzing the cycloaddition of carbon dioxide and epoxy compounds and the copolymerization of sulfur dioxide and epoxides, belonging to the field of material chemical industry. Background Art

[0002] Due to excessive fossil fuel consumption and industrial waste emissions, atmospheric concentrations of gases such as carbon dioxide (CO2) and sulfur dioxide (SO2) continue to rise. The accumulation of CO2 has triggered global climate change, while SO2 is a key pollutant contributing to environmental and health problems such as acid rain and respiratory diseases, posing a threat to ecosystems and sustainable social development. However, synthesizing high-value-added chemicals from CO2 and SO2 is an important avenue for their resource utilization. In particular, the synthesis of cyclic carbonates from CO2 and epoxides is considered a 100% atom-economic process, with the resulting products finding widespread application in lithium battery electrolytes, polar aprotic solvents, and polymer monomers. Furthermore, the copolymerization of SO2 with epoxides can directly produce biodegradable polysulfites, which have shown potential in specialized packaging, drug delivery, and functional materials. Given the thermodynamic stability and kinetic inertness of CO2 molecules, as well as the toxicity and difficulty in regulating the reactivity of SO2 molecules, the development of catalytic systems that can efficiently and selectively catalyze these two transformations, particularly enabling controlled SO2 copolymerization under mild conditions, is highly attractive.

[0003] While homogeneous catalysts (such as metal salts and complexes) exhibit moderate activity and selectivity in these reactions, their difficulty in recycling and reuse limits their economic and environmental viability in industrial applications. Recent advances in immobilization of heterogeneous catalysts, such as traditional metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been limited in their application to SO₂ copolymerization. These catalysts often face challenges such as complex synthesis, limited stability (especially in the presence of SO₂ or in acidic environments), and insufficient catalytic efficiency under mild conditions (particularly for SO₂ copolymerization). Therefore, the development of multifunctional heterogeneous catalysts that combine facile preparation, excellent stability, high catalytic activity (especially for SO₂ copolymerization under mild conditions), and good recyclability is crucial. Ionic metal-organic frameworks (iMOFs), with their unique anionic and cationic properties, tunable pore environments, excellent stability, and ease of integrating active sites, offer a promising platform for the efficient and simultaneous catalysis of CO₂ cycloaddition and SO₂ copolymerization. Summary of the Invention

[0004] In view of the harsh reaction conditions of the cycloaddition of carbon dioxide and epoxy compounds and the copolymerization of sulfur dioxide and epoxides, the low activity of traditional catalysts, the difficulty in separation and the pollution of the environment, the present invention provides a method for preparing ionic metal-organic framework materials.

[0005] The invention comprises the following steps: mixing a metal nitrate, a pyrazine carboxylic acid and 1,4-diazabicyclo[2.2.2]octane in a solvent, dissolving the mixture by ultrasonication, transferring the mixture to a stainless steel hydrothermal reactor, heating the mixture at 120-150°C for 48-72 hours, cooling the mixture to room temperature, performing solid-liquid separation, washing the solid and vacuum drying the mixture to obtain a metal organic framework material; and mixing the metal organic framework material and a halogen derivative in acetonitrile, reacting the mixture at 60-80°C in a nitrogen atmosphere for 24-30 hours, cooling the mixture to room temperature, performing solid-liquid separation, washing the solid product and vacuum drying the mixture to obtain an ionic metal organic framework material.

[0006] The metal nitrate is one of nickel nitrate hexahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, copper nitrate hexahydrate, and manganese nitrate hexahydrate. The molar ratio of the metal nitrate to the pyrazine carboxylic acid is 2-3:1-3, and the molar ratio of the metal nitrate to 1,4-diazabicyclo[2.2.2]octane is 2-3:4.

[0007] The pyrazine carboxylic acid is one of 2,5-pyrazinedicarboxylic acid, 2,3,5,6-pyrazinetetracarboxylic acid, and 4,4',4",4"'-(pyrazine-2,3,5,6-tetraalkyl)tetrabenzoic acid.

[0008] The halogen derivative is one of iodomethane, bromoethanol, benzyl chloride, and methyl trifluoromethanesulfonate, and the molar ratio of the halogen derivative to the metal organic framework material is 1-3:1.

[0009] The solvent is one of methanol, ethanol, water, N,N-dimethylformamide and N,N-dimethylacetamide.

[0010] Another object of the present invention is to apply the ionic metal-organic framework material prepared by the above method to the catalytic cycloaddition reaction of carbon dioxide and an epoxy compound. Specifically, the ionic metal-organic framework material and the epoxy compound are sequentially added to an autoclave (the molar ratio of catalyst:epoxide is 1:100-1000). Before the carbon dioxide cycloaddition, the autoclave is purged three times with 99.99% carbon dioxide by volume at room temperature to remove impurities. Then, carbon dioxide by volume is introduced, and the initial carbon dioxide pressure is adjusted (0.1-1.5 MPa). The reaction temperature (80-120°C) and reaction time (2-10 hours) are set. After the reaction is completed, the autoclave is cooled to below 10°C in an ice bath, the residual gas is slowly released, and the catalyst and reaction product are filtered and collected. The reaction product is a cyclic carbonate.

[0011] Another object of the present invention is to use the ionic metal-organic framework material prepared by the above method in catalyzing the copolymerization reaction of sulfur dioxide and an epoxy compound. Specifically, the ionic metal-organic framework material and the epoxy compound are sequentially added to an autoclave (the molar ratio of catalyst:epoxide is 1:100-1000). Before the sulfur dioxide copolymerization reaction, the autoclave is purged three times with nitrogen gas at a volume concentration of 99.99% at room temperature to remove impurities. Then, sulfur dioxide with a volume concentration of 99.99% is introduced. The initial sulfur dioxide pressure is adjusted to 0.2 MPa, and the reaction temperature (80-120° C.) and reaction time (2-10 hours) are set. After the reaction is completed, the temperature is lowered to room temperature, the reactants are dissolved in dichloromethane, and methanol is added for precipitation. The precipitate is collected by filtration, washed with methanol 3-4 times, and then dried to obtain a copolymer of sulfur dioxide and epoxide, namely, polysulfite.

[0012] The epoxy compound is one of propylene oxide, epichlorohydrin, 1,2-butylene oxide, styrene oxide, glycidyl ether, and cyclohexene oxide.

[0013] Compared with the prior art, the present invention has the following advantages: (1) The method of the present invention synthesizes a columnar ultramicroporous metal-organic framework material and introduces a halogen derivative through a quaternization reaction, so that the material has metal sites, halogen anion sites and hydrogen bond donor sites, which makes the material have Lewis acidity, basicity and hydrogen bonding force; (2) The ionic metal-organic framework material prepared by the present invention exhibits excellent catalytic activity and high selectivity in the conversion of carbon dioxide and epoxide into cyclic carbonates and the copolymerization of sulfur dioxide and epoxide into polysulfite under the conditions of no co-catalyst and solvent. It is easy to recover after the catalysis is completed and easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a Fourier transform infrared spectrum (FTIR) of the ionic metal organic framework material of Example 1; Figure 2 is the X-ray diffraction (XRD) pattern; Figure 3 It is the nitrogen adsorption-desorption curve and pore size distribution diagram; Figure 4 The cyclic carbonate prepared in Example 1 1 H NMR spectrum; Figure 5 The polysulfite prepared in Example 1 1 H NMR spectrum; Figure 6This is the Fourier transform infrared spectrum (FTIR) of polysulfite. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below through examples and drawings, but the protection of the present invention is not limited to the contents described. Example 1

[0016] (1) 0.4362 g of nickel nitrate hexahydrate, 0.3811 g of 4,4',4",4"'-(pyrazine-2,3,5,6-tetraalkyl)tetrabenzoic acid and 0.3366 g of 1,4-diazabicyclo[2.2.2]octane were mixed and dissolved in 60 mL of N,N-dimethylformamide. The resulting mixture was ultrasonicated for 30 min and then transferred to the inner lining of a hydrothermal reactor. The mixture was heated at 150 °C for 72 h. After cooling to room temperature, the solid-liquid separation was performed. The solid was washed three times with solvent N,N-dimethylformamide and then dried in a vacuum drying oven at 120 °C for 24 h to obtain a metal organic framework material (Ni-MOF-1). (2) 0.4180 g of metal-organic framework material (Ni-MOF-1), 0.1250 g of bromoethanol, and 15 mL of acetonitrile were added to a 100 mL Schlenk tube in sequence. The Schlenk tube was evacuated and filled with nitrogen. After three cycles, the Schlenk tube was placed in an oil bath and heated at 80 °C for 24 h. After the reaction was completed, it was cooled to room temperature. The solid product was collected by vacuum filtration, washed three times with acetonitrile, and placed in a vacuum drying oven at 60 °C for 24 h to obtain an ionic metal-organic framework material (Ni-MOF-BrOH-1). Fourier transform infrared spectroscopy (FTIR) was used to characterize the changes of metal organic framework materials before and after quaternization reaction. Figure 1 As shown, in Ni-MOF-BrOH-1, 1250 cm -1 A vibration peak appears at , which is the bond between the pyrazine ring nitrogen and the ethyl carbon in the quaternary ammonium salt (CN + ) stretching vibration, which does not exist in Ni-MOF-1; In addition, the 2950cm -1 A new vibration peak also appeared at the + -The stretching vibration of the methylene group in the metal organic framework material; This indicates that the metal organic framework material and bromoethanol have successfully undergone quaternization reaction to generate an ionic metal organic framework material. Powder X-ray diffraction (XRD) was used to characterize the changes in the crystal structure of the metal organic framework material before and after the quaternization reaction. Figure 2It can be seen that the crystal structure of the ionic metal organic framework material is still maintained after quaternization. The nitrogen adsorption and desorption experiment was used to characterize the changes in the specific surface area and pore size distribution of the metal organic framework material before and after the quaternization reaction. The specific surface area of ​​the metal organic framework material Ni-MOF-1 is 909m 2 / g, the specific surface area of ​​the ionic metal organic framework material Ni-MOF-BrOH is 694m 2 / g, its specific surface area is reduced after modification (see Figure 3 ); (3) 2 mL of epichlorohydrin and 0.0543 g of Ni-MOF-BrOH-1 (catalyst:epoxide molar ratio = 1:500) were added to a 50 mL autoclave in sequence. Before the carbon dioxide cycloaddition, the autoclave was purified three times with 99.99% carbon dioxide to remove impurities. Then, 99.99% carbon dioxide was introduced. After the introduction, the inlet and outlet valves were closed. The speed was set to 280 r / min, the temperature was set to 100 ° C, the carbon dioxide pressure was set to 1.0 MPa, and the reaction time was set to 8 h. After the reaction was completed, the autoclave temperature was cooled to below 10 ° C in an ice bath, and the residual gas was slowly released. Finally, the reaction mixture was filtered to collect the catalyst and the reaction product 3-chloropropylene carbonate. The product yield was 99% and the selectivity was 99%. 1 The obtained product was characterized by H NMR spectrum. Figure 4 The chemical shifts of the product 3-chloropropylene carbonate in the figure are d=5.06ppm, 4.63ppm, 4.43ppm, 3.87ppm, and 3.75ppm, respectively. This confirms that carbon dioxide and epichlorohydrin undergo a cycloaddition reaction to produce 3-chloropropylene carbonate.

[0017] (4) 2 mL of cyclohexene oxide and 0.0543 g of Ni-MOF-BrOH-1 were added to a 50 mL autoclave in sequence; then nitrogen with a volume concentration of 99.99% was introduced into the autoclave, and after nitrogen was introduced three times, sulfur dioxide with a volume concentration of 99.99% was introduced into the autoclave, and the sulfur dioxide pressure was 0.2 MPa; after the introduction was completed, the inlet and outlet valves were closed, the speed was set to 280 r / min, the temperature was set to 110 ° C, and the reaction time was 8 h; after the reaction was completed, dichloromethane was used to dissolve the reaction product, and then methanol was added for precipitation. After filtering, a precipitate was obtained, and the precipitate was washed with methanol three times. The washed precipitate was placed in a vacuum drying oven and vacuum dried at 40 ° C for 24 h to obtain a copolymer of sulfur dioxide and epoxy compound, wherein the conversion rate of cyclohexene oxide was 90% ( 1 H NMR spectrum is shown in Figure 5 ), the selectivity of polysulfite is 80%; the obtained product is characterized by Fourier transform infrared spectroscopy (FTIR), and the results are shown in Figure 6 , shown in the figure at 1208cm -1 and 728cm -1 Vibration peaks related to S=O and SO appeared at , confirming the presence of sulfur dioxide on the main chain; Example 2

[0018] (1) 0.4365 g of cobalt nitrate hexahydrate, 0.3811 g of 4,4',4",4"'-(pyrazine-2,3,5,6-tetraalkyl)tetrabenzoic acid and 0.3366 g of 1,4-diazabicyclo[2.2.2]octane were mixed and dissolved in 60 mL of N,N-dimethylformamide. The resulting mixture was ultrasonicated for 30 min and then transferred to the inner lining of a hydrothermal reactor. The mixture was heated at 150 °C for 72 h. After cooling to room temperature, the solid-liquid separation was performed. The solid was washed three times with solvent N,N-dimethylformamide and then placed in a vacuum drying oven at 120 °C for 24 h to obtain a metal organic framework material (Co-MOF-1). (2) 0.4183 g of metal-organic framework material (Co-MOF-1), 0.1250 g of bromoethanol, and 15 mL of acetonitrile were added to a 100 mL Schlenk tube in sequence. The Schlenk tube was evacuated and filled with nitrogen. After three cycles, the Schlenk tube was placed in an oil bath and heated at 80 °C for 24 h. After the reaction was completed, it was cooled to room temperature. The sample was collected by vacuum filtration, washed three times with acetonitrile, and then placed in a vacuum drying oven at 60 °C for 24 h to obtain an ionic metal-organic framework material (Co-MOF-BrOH-1). (3) The ionic metal organic framework material prepared in step (2) was applied to the addition reaction of epichlorohydrin and carbon dioxide, and the implementation method was the same as that of Example 1 to obtain a cyclic carbonate ester, a cycloaddition product of carbon dioxide and an epoxy compound, with a product yield of 99% and a selectivity of 99%; (4) The ionic metal organic framework material obtained in step (2) is applied to the copolymerization reaction of cyclohexene oxide and sulfur dioxide, and the implementation method is the same as that of Example 1 to obtain a copolymer of sulfur dioxide and epoxy compound, with a conversion rate of cyclohexene oxide of 90% and a selectivity of polysulfite of 80%. Example 3

[0019] (1) 0.4362 g of nickel nitrate hexahydrate, 0.1742 g of 2,3,5,6-pyrazinetetracarboxylic acid, and 0.3366 g of 1,4-diazabicyclo[2.2.2]octane were mixed and dissolved in 60 mL of ethanol. The resulting mixture was ultrasonicated for 30 min and then transferred to the inner lining of a hydrothermal reactor. The mixture was heated at 150 °C for 72 h. After cooling to room temperature, the solid-liquid separation was performed. The solid was washed three times with N,N-dimethylformamide solvent and then dried in a vacuum drying oven at 120 °C for 24 h to obtain a metal organic framework material (Ni-MOF-2). (2) 0.2278 g of metal-organic framework material (Ni-MOF-2), 0.1250 g of bromoethanol, and 15 mL of acetonitrile were added to a 100 mL Schlenk tube in sequence. The Schlenk tube was evacuated and filled with nitrogen. After three cycles, the Schlenk tube was placed in an oil bath and heated at 80 °C for 24 h. After the reaction was completed, it was cooled to room temperature. The sample was collected by vacuum filtration and washed three times with acetonitrile. It was then placed in a vacuum drying oven at 60 °C for 24 h to obtain an ionic metal-organic framework material (Ni-MOF-BrOH-2). (3) The ionic metal organic framework material prepared in step (2) was applied to the addition reaction of epichlorohydrin and carbon dioxide, and the implementation method was the same as that of Example 1 to obtain a cyclic carbonate ester, a cycloaddition product of carbon dioxide and an epoxy compound, with a product yield of 99% and a selectivity of 99%; (4) The ionic metal organic framework material obtained in step (2) is applied to the copolymerization reaction of cyclohexene oxide and sulfur dioxide, and the implementation method is the same as that of Example 1 to obtain a copolymer of sulfur dioxide and epoxy compound, with a conversion rate of cyclohexene oxide of 90% and a selectivity of polysulfite of 80%. Example 4

[0020] (1) 0.4462 g of zinc nitrate hexahydrate, 0.3811 g of 4,4',4",4"'-(pyrazine-2,3,5,6-tetraalkyl)tetrabenzoic acid and 0.3366 g of 1,4-diazabicyclo[2.2.2]octane were mixed and dissolved in 60 mL of N,N-dimethylformamide. The resulting mixture was ultrasonicated for 30 min and then transferred to the inner lining of a hydrothermal reactor. The mixture was heated at 150 °C for 72 h. After cooling to room temperature, the solid-liquid separation was performed. The solid was washed three times with solvent N,N-dimethylformamide and then dried in a vacuum drying oven at 120 °C for 24 h to obtain a metal organic framework material (Zn-MOF-1). (2) 0.4247 g of metal-organic framework material (Zn-MOF-1), 0.1641 g of methyl trifluoromethanesulfonate, and 15 mL of acetonitrile were added to a 100 mL Schlenk tube in sequence. The Schlenk tube was evacuated and filled with nitrogen. After three cycles, the Schlenk tube was placed in an oil bath and heated at 80 °C for 24 h. After the reaction was completed, it was cooled to room temperature. The sample was collected by vacuum filtration and washed three times with acetonitrile. It was then placed in a vacuum drying oven at 60 °C for 24 h to obtain an ionic metal-organic framework material (Zn-MOF-CF3-1). (3) The ionic metal organic framework material prepared in step (2) was applied to the addition reaction of epichlorohydrin and carbon dioxide, and the implementation method was the same as that of Example 1 to obtain a cyclic carbonate ester, a cycloaddition product of carbon dioxide and an epoxy compound, with a product yield of 99% and a selectivity of 99%; (4) The ionic metal organic framework material obtained in step (2) is applied to the copolymerization reaction of cyclohexene oxide and sulfur dioxide, and the implementation method is the same as that of Example 1 to obtain a copolymer of sulfur dioxide and epoxy compound, with a conversion rate of cyclohexene oxide of 90% and a selectivity of polysulfite of 80%.

Claims

1. A method for preparing an ionic metal-organic framework material, characterized by: A metal nitrate salt, pyrazine carboxylic acid and 1,4-diazabicyclo[2.2.2]octane are mixed in a solvent, ultrasonically dissolved, and then transferred to a hydrothermal reactor, heated at 120-150°C for 48-72 hours, cooled to room temperature, solid-liquid separation, solid washing and vacuum drying to obtain a metal organic framework material; a metal organic framework material and a halogen derivative are mixed in acetonitrile, reacted at 60-80°C in a nitrogen atmosphere for 24-30 hours, cooled to room temperature, solid-liquid separation, solid product washing, and vacuum drying to obtain an ionic metal organic framework material.

2. The method for preparing an ionic metal organic framework material according to claim 1, wherein: The metal nitrate is one of nickel nitrate hexahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, copper nitrate hexahydrate, and manganese nitrate hexahydrate. The molar ratio of the metal nitrate to the pyrazine carboxylic acid is 2-3:1-3, and the molar ratio of the metal nitrate to 1,4-diazabicyclo[2.2.2]octane is 2-3:

4.

3. The method for preparing an ionic metal organic framework material according to claim 1, wherein: The pyrazine carboxylic acid is one of 2,5-pyrazinedicarboxylic acid, 2,3,5,6-pyrazinetetracarboxylic acid and 4,4',4",4"'-(pyrazine-2,3,5,6-tetraalkyl)tetrabenzoic acid.

4. The method for preparing an ionic metal organic framework material according to claim 1, wherein: The halogen derivative is one of iodomethane, bromoethanol, benzyl chloride and methyl trifluoromethanesulfonate, and the molar ratio of the halogen derivative to the metal organic framework material is 1-3:

1.

5. The method for preparing an ionic metal organic framework material according to claim 1, wherein: The solvent is one of methanol, ethanol, water, N,N-dimethylformamide and N,N-dimethylacetamide.

6. Use of the ionic metal organic framework material prepared by the preparation method of the ionic metal organic framework material according to claim 1 in catalyzing the cycloaddition reaction of carbon dioxide and epoxy compounds to produce cyclic carbonates.

7. Use of the ionic metal organic framework material prepared by the preparation method of the ionic metal organic framework material according to claim 1 in catalyzing the copolymerization reaction of sulfur dioxide and epoxy compounds to produce polysulfite.

8. The use according to claim 6 or 7, characterized in that: The epoxy compound is one of propylene oxide, epichlorohydrin, 1,2-butylene oxide, styrene oxide, glycidyl ether, and cyclohexene oxide.

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